1. Summary of the Invention
The present invention relates to solar heat collectors, and in particular relates to a very simple unit with efficient heat transfer characteristics.
2. Description of the Prior Art
Many different systems have been designed for use in connection with solar heat collectors. The art contains examples of single tubes, aligned in fixed beds to evaporate water and produce steam, conical collectors with central fluid transfer systems, spherical units, and many other different styles of units. All of these fixed type of units suffer from the disadvantage of being immobile, and thus being incapable of compensating for the daily motion of the sun from horizon to horizon. In order to overcome this type of problem, various complex units have been designed. An exemplary unit is that disclosed in U.S. Pat. No. 3,884,217 of Wartes which utilizes plural prismatic, independently adjustable reflectors which pivot to collect the sun's rays, and reflect them to a second reflective surface which then directs them to the actual heat transfer section. The whole collector is also pivoted to aid the compensating for the sun's daily motion. The unit is thus quite complex and expensive and requires considerable mechanical manipulation in order to function properly.
The complexity of this type of system is overcome, for example, by the system disclosed by Futch in U.S. Pat. No. 4,086,911. This system merely uses numerous tubes positioned in a truncated cone designed to absorb heat. Such a simple system, however, is quite inefficient as it cannot be moved in order to increase the amount of energy absorbed to the level of complex systems.
Additionally, various other attempts at producing functional solar heating systems are disclosed in U.S. Pat. Nos. 4,109,640 of Smith; 4,119,085 of Knowles et al, and 4,138,061 of Besack. All of these lack efficiency or are quite complex.
U.S. Pat. No. 4,015,584 of Haberman discloses another apparatus for solar heat collecting. The apparatus utilizes a plurality of vertical tubes, and the structural requirements for window mounting result in a relatively complex unit of limited size and heating capacity. Thus, it is of relatively limited utility as compared to a fixed position, high-surface-area unit. On the other hand, Wilson, in U.S. Pat. No. 3,954,097, discloses a simpler unit, in that a vertical tube is used to both provide fluid flow and support a parabolic surface. However, in order to provide the fluid flow, a complex, expensive structure is necessary. Further, a significant relatively flat, external cross-sectional surface area is disclosed, which would present dangers when roof-mounted as suggested, due to possible wind damage.
It is therefore an object of the present invention to develop a simple solar heat collector which is more efficient that the "flat plate" type of units that are normally placed on rooftops, and also close to the efficiency of the units which are movable in two planes (azimuth and elevation) without requiring the complex structure needed for such motion. It is a further object of the present invention to provide maximum surface area, with minimum use of space during orientation or rotation of the unit. Also an object is to provide such a unit that has the ability to withstand winds of relatively high speed and that is rotatable during such high wind velocities, without great increase in structural weight.